Just Explain It: Your Brain On Lying

Zelkadis Elvi and Lauren Lyster

Just Explain It - News•April 24, 2013

If we were all like Pinocchio, it would be easy to spot when someone was telling a lie. Their noses would grow. But we’re not like Pinocchio. So for many years, scientists have been trying to pinpoint the telltale signs that someone is telling a tall tale.

Besides intuition or visually observing a person’s behavior, the most common method of lie detection is the polygraph. It’s been around since the early 1900s and measures things like your heart rate, respiration, perspiration and overall anxiety to determine if you're telling the truth.

But some scientists aren’t satisfied with that.

In this Just Explain It, we’ll look at how a new way of measuring brain activity may help researchers actually see when a person is lying.

It’s called functional magnetic resonance imaging, or fMRI. I know, that's a mouthful, but one company, No Lie MRI, believes the technology can expose a lie using scans of the brain’s activity. Here’s the theory. When someone tells a lie, their brain has to do more work than when they’re telling the truth – the blood flow increases. fMRI scans expose that extra work. Areas of the brain where blood flow has increased indicate deception and are highlighted with bright colors.

The company also claims that fMRIs are accurate 90 to 99% of the time. That's pretty remarkable when you compare that to polygraphs, which perform with about 60% accuracy.

But studies of the brain have found that no two brains are alike - they’re like fingerprints, but more complex. The patterns of brain activity are actually different depending on the lie being told. A little white lie might look different from full on deception.

And that leads many in the neuroscience field to think companies like No Lie MRI might themselves be stretching the truth a little bit. They believe more research is needed to draw indisputable conclusions on a regular basis.

The debate has also spread to the courtroom. Some lawyers and judges aren’t convinced the technology is foolproof either. In recent court cases, fMRI evidence was ruled inadmissible because the findings aren’t widely accepted by the scientific community.

In the end, the data collected might help researches begin to understand the truth about lies. And at some point, experts say they can see a time when brain scans will replace the polygraph.

But does all of this mean that people will stop telling lies?

Let us know what you think. Give us your feedback in the comments below or on Twitter using #YahooNews and #JustExplainIt.